The present invention relates to screw-type cutter drums for mining machines, and more particularly to cutter drums of the type having cutter picks carried on helical ribs on the body of the drum and additional cutter picks on the end face of the drum adjacent the working face.
Drum cutters for mining coal, or other minerals, are known having helical ribs on the circumferential surface of the drum body which function to convey the coal away from the working face and which have cutter picks mounted on their outer surfaces. Cutter picks have also been mounted on the end of the cutter drum in a radial line and spaced at varying radial distances from the axis, as shown, for example, in German Pat. No. 1,216,821.
Cutter drums are also known as shown, for example, in German Gebrauchsmuster No. 1,993,515 in which cutter picks are mounted on the circumference and surface of a mounting disc attached to the working face end of the cutter drum. The circumference of such a mounting disc has interruptions or gaps corresponding in position to the channels between the helical ribs on the drum body and the radial projections between these gaps coincide in position with the end surfaces of the helical ribs. The cutter picks are mounted on the radial projections and the end surface of the mounting disc and are arranged in radial rows with non-uniform radial spacing between picks. Such an arrangement of cutter picks could, of course, also be attached directly to the end surface of the drum and the end surfaces of the helical ribs.
To improve pickup of the coal or other material being mined by the cutter drum, the channels between the helical ribs should terminate at the working face end in openings of the largest possible cross section in order to facilitate pickup of the mined material without further breakage and to minimize the formation of dust. This, however, results in a large space, or circumferential distance, between the cutter picks on opposite sides of each such opening. Since the cutter drum is continuously moved transversely of its axis by the mining machine, the cutter picks adjacent the openings are always required to make the deepest cuts, and smooth operation of the cutter drum is difficult to obtain.